Method of and apparatus for forming a sand mould for use in the manufacture of a cast iron pipe

ABSTRACT

Forming a sand mould prior to centrifugally casting a cast iron pipe by locating a mould containing flask against a sand blow head, bringing a plate against the other end of the flask and passing a mandrel having an oversized head through the plate and locating one end of the mandrel against the blow head, blowing sand into the annulus so formed between the mandrel and flask, compacting the sand at each end of the flask and compacting the remainder of the sand by withdrawing the mandrel from the flask so that the head of the mandrel effects the compacting.

Muted States Patent 1191 1111 3,837,389 Provan Sept. 24, 1974 [54]METHOD OF AND APPARATUS FOR 3,165,794 1/1965 Johnston 164/177 FORMING ASAND MOULD O USE IN 3,221,377 12/1965 Johnston..... THE MANUFACTURE OF ACAST IRON 3,255,497 6/1966 Johnston 164/177 PIPE Inventor: Duncan WhyteProvan, Shrewsbury,

England Assignee: Glynwed Foundries Limited, Bilston,

Staffordshire, England Filed: Feb. 6, 1973 Appl. No.: 330,013

Foreign Application Priority Data Feb. 14, 1972 Great Britain 006710/72U.S. Cl. 164/33, 164/177 Int. Cl. B22c 13/10 Field of Search 164/20, 33,176, 177, 178

Primary ExaminerJ. Spencer Overholser Assistant Examiner-John E. RoethelAttorney, Agent, or Firm-Bacon & Thomas Forming a sand mould prior tocentrifugally casting a cast iron pipe by locating a mould containingflask against a sand blow head, bringing a plate against the other endof the flask and passing a mandrel having an oversized head through theplate and locating one end of the mandrel against the blow head, blowingsand into the annulus so formed between the mandrel and flask,compacting the sand at each end of the flask and compacting theremainder of the sand by withdrawing the mandrel from the flask so thatthe head of the mandrel effects the compacting.

ABSTRACT 9 Claims, 8 Drawing Figures PAIENIEUSEPZMBM v I swearsPAIENIEDSEPwQM 3.8%13639 sum nor a FIGA METHOD OF AND APPARATUS FORFORMING A SAND MOULD FOR USE IN THE MANUFACTURE OF A CAST IRON PIPE Thisinvention relates to a method of and apparatus for forming a sand mouldfor use in the manufacture of a cast iron pipe. Such pipe issubsequently manufactured by spinning molten metal within the sand mouldso formed.

The technique of forming cast iron pipes by spinning molten metal withina preformed sand mould has been known for many years and is sometimescalled centrifugal casting. The sand mould is formed within a tubularenclosure normally known as a flask. Such a flask is open at both endsand these ends are closed while the sand mould is being formed. Themoulded sand is then retained within the flask during the formation ofthe pipe. When the pipe is formed, it is removed from its flask and thesand may then be reused to form another mould.

In order to form a hollow interior to the sand mould, a mandrel isinserted to lie axially within the flask and this mandrel remains inposition while the sand is being blown into the annulus between themandrel and the flask. The mandrel is then withdrawn from the flaskleaving the moulded sand ready to receive the molten metal at asubsequent stage in the process of forming the cast iron pipe.

Although the sand is blown under pressure into the annulus between themandrel and the flask, in order to provide an accurately dimensionedcast iron pipe it is necessary to compact the sand so as to avoid thesurface of the mould from being disrupted by the molten metal. Thiscompacting of the sand has previously been accomplished by providingclosure members for the ends of the flask which closure members haveparts which are movable within the flask to compact the sand at the endsof the flask where the rims of the pipe are to be formed. However,previous proposals have not suggested a way of compacting the sand alongthe entire exposed surface of the sand mould and therefore over theareas where the sand has not been compacted the resultant pipe may wellbe of inaccurate dimenslons.

It is the main object of this invention to provide a method andapparatus for forming a sand mould for the manufacture of a long pipeof, for example, between 6ft and 8ft in length which results in a moreaccurately formed pipe than has hitherto been possible.

According to the present invention there is provided a method of forminga sand mould for use in the manufacture of a pipe, including the stepsof locating one end of a cylindrical flask against a sand blow head,moving a plate carrying a first socket forming sleeve and compactingring so that the plate locates against the other end of the flask,feeding a cylindrical mandrel having an oversized head through anaperture in the plate until the head enters a second socket formingsleeve mounted on the blow head, blowing sand into the space so formedbetween the flask and mandrel, compacting the sand at each end of theflask by longitudinal movement of the compacting ring and second socketforming sleeve within the flask and withdrawing the mandrel so that thehead. thereof compacts and smooths the inner wall of the sand.

The invention also includes apparatus for forming a sand mould for usein the manufacture of a pipe, in-

eluding a cylindrical flask, a sand blow head, a plate movable towardsand away from the blow head to clamp the flask therebetween, a firstsocket forming sleeve carried by the plate and positioned to enter theflask on clamping thereof, a compacting ring carried by the plate andcapable of movement relative to the plate axially of the flask, a secondsocket forming sleeve mounted on the blow head and positioned to enterthe flask on clamping thereof, said second socket forming sleeve beingcapable of movement relative to the blow head axially of the flask andan axially movable mandrel having an oversized head, said mandrel beingmovable within the flask from a position in which its head has enteredthe second socket forming sleeve to a position in which its head hasentered the first socket forming sleeve.

Preferably, the blow head and plate are both provided with locationmeans for accurately positioning the flask on clamping thereof.

Preferably, the mandrel passes through an aperture in the plate and theblow head is provided with means for accurately positioning the head ofthe mandrel in the second socket forming sleeve. Said means may includea projection on the blow head which enters a recess in the head of themandrel for guiding the head of the mandrel to within the second socketforming sleeve.

Conveniently, the plate is slidably mounted and is moved by actuation ofa first pair of piston and cylinder assemblies.

Preferably, the compacting ring is movable by actuation of a second pairof piston and cylinder assemblies which are mounted on the plate.

One embodiment of apparatus constructed in accordance with the presentinvention will now be described, by way of example only, and withreference to the accompanying drawings in which:

FIG. 1 is a side elevation of a flask within which a sand mould may beformed;

FIGS. 2A and 2B are part sectional sideelevation views of apparatusaccording to the invention at the commencement of a mould forming cycle;

FIG. 3 is a cross-sectional view on the line III-III of FIG. 2B;

FIG. 4 is a view similar to FIG. 2 but with the apparatus in a positionafter the mould has been partially formed; a

FIG. 5 is a fragmentary sectional view of part of the apparatus of FIG.4 showing the blow head end of the flask before the sand is compacted;

FIG. 6 is a view similar to FIG. 5 but of the other end of the flaskshowing the position of the apparatus before the sand is compacted; and

FIG. 7 is a view similar to FIGS. 2 and 4 but showing the apparatus in aposition in which the mould is being further formed.

In the drawings there is indicated a flask 1 of known construction whichis cylindrical and of a length equal to the length of the cast iron pipeto be formed. The flask 1 is provided with a pair of spaced wheelmembers 2 which run on rails 3 mounted on a suitable form of base 4 sothat the flask 1 may be conveyed through various stations of which theillustrated sand mould forming station is the first during the formationof a cast iron pipe. The construction of the remaining stations form nopart of the present invention and therefore will not be described.

At the mould forming station illustrated in the drawings, there isprovided flask feeding means generally indicated at 5 which is basicallyof known construction and enables the flask 1 to be fed axially towardsor away from a sand blow head generally indicated at 6. The flaskfeeding means 5 includes a support structure 7 carrying a ram 8 which iscapable of moving a flask support structure 9 slidably mounted bysliding bearings 10 on slide rods 11. The flask feeding means alsoincludes a further ram 12 which moves a cradle means 13 on which theflask l is received and which discharges the flask after the sand mouldhas been formed. The provision of ram 8 at the mould forming stationenables the flask 1 to be moved axially for the formation of the mouldto commence.

At the mould forming station there is provided the sand blow head 6previously mentioned which includes location means 14 which enablesaccurate location of one end of the flask 1 at the blow head. As will beseen from the drawing, the location means 14 is in the form of a ringhaving its inner peripheral edge chamfered at 15 for reception of oneend of the flask l. The location means 14 enables accurate location ofone end of the flask l atthe blow head 6.

Mounted on the blow head 6 is a socket forming sleeve 16 which has anexternal profile similar to the external profile of a socket end of thepipe to be formed. This socket forming sleeve 16 is movable axially ofthe flask 1 in relation to the blow head 6 by hydraulic or pneumaticpressure being applied to a chamber 17. The socket forming sleeve 16 maybe spring returned or returned by the hydraulic or pneumatic pressurebeing applied to a return chamber.

The blow head 6 also includes a projection 18 which is tapered, thepurpose of which will be described later. The blow head also includesblow holes 19 for blowing sand from a duct 20 into the flask 1.

At the other end of the flask 1 there is mounted a plate 21 slidable onrails 22 and movable axially of the flask 1 by a first pair of pistonand cylinder assemblies 23. The rails 22 are mounted by brackets 24 on asupporting frame structure 25. The plate 21 is provided with locationmeans 26 similar to the location means 14 at the blow head end foraccurately locating the flask 1 at the plate end during clamping. Thelocation means 26 is in the form of a ring having a chamfer 27 to assistin the location.

The plate 21 carries a socket forming sleeve 28 which has an externalprofile similar to the external profile of socket forming sleeve 16. Theplate 21 also carries a compacting ring 29 which is movable in relationto the plate 21 and axially of the flask 1. The ring 29 is movable byactuation of a second pair of piston and cylinder assemblies 30 carriedby the plate 21. The compacting ring 29 is connected to the second pairof piston and cylinder assemblies 30 by a yoke 31.

Passing through an aperture 32 in the plate 21 is a mandrel 33 with ahead 34 which has an outside diameter greater than the diameter of themain length of the mandrel 33. Thus, the head 34 is oversized inrelation to the mandrel. The mandrel 33 and head 34 are movable axiallyof the flask 1 by a single piston and cylinder assembly 35 which issupported by the main frame structure 25.

All of the piston and cylinder assemblies and rams mentioned above maybe hydraulically operated.

To form a sand mould in accordance with the invention, the flask 1 isbrought on rails 3 to the position illustrated in FIG. 2B. The flask 1is then held in this position on track 3. The ram 8 is then actuated tomove the flask 1 so that the blow head end thereof engages the locationmeans 14 and by virtue of chamfered edge 15 thereof the blow head end offlask 1 is correctly located on the blow head as illustrated in FIG. 4.It will be noticed that when the flask is in position on the blow headthe blow holes 19 provide communication from the sand duct 20 to withinthe flask l.

The piston and cylinder assemblies 23 are then actuated and the plate 21together with the socket forming sleeve 28 and compacting ring 29 aremoved towards the other end of the flask 1. This other end of the flask1 engages the location means 26 and because of the chamfered edge 27accurately locates the location means over the end of the flask 1. Thus,on clamping, the flask 1 will be in its correct position in relation tothe plate 21. The clamped position is illustrated in FIGS. 4 and 7.

The piston and cylinder assembly 35 is then actuated to feed the mandrel33, together with its head 34, so that the head 34 locates within thesocket forming sleeve 16 as illustrated in FIG. 4. This location isachieved by the tapered configuration of projection 18 which engageswithin a recess within the head 34.

The flask is now located in position with the mandrel therein andbetween the flask and the mandrel there is an annular space whichreceives sand to form the sand mould. Sand is blown via duct 20 throughblow holes 19 into the space between the flask 1 and mandrel 33 to fillthis space completely thereby compacting the sand and blow-forming apipe mold. Thereafter, hydraulic pressure is applied to chamber 17 tomove the socket forming sleeve axially inwardly of the flask and therebycompact the sand at the blow head end of the flask and form andconsolidate this socket part of the mould. The position of the blow headend of the apparatus prior to the socket forming sleeve being moved isillustrated in FIG. 5 and after the socket forming sleeve has been movedthe position is as illustrated in FIG. 4. It will thus be seen thatmovement of the socket forming sleeve compacts the sand in the areawhere the socket is to be formed on the pipe.

Simultaneously, the piston and cylinder assemblies 30 are actuated sothat the compacting ring 29 will move axially inwardly of the flask 1and compact the sand at the other end of the mould in the neighbourhoodof the other socket. The position of the parts at this end of the flaskprior to the compacting ring being moved are illustrated in FIG. 6whereas after the compacting ring has been moved the position is asillustrated in FIG. 4.

The piston and cylinder assembly 35 is then reverse actuated to retractthe mandrel 33 and its head 34 as illustrated in FIG. 7. The fact thatthe head 34 is oversized in relation to the mandrel 33 will mean thatduring this retraction the internal surface of the sand mould will becompacted and smoothed over its entire length by the head 34, apart fromthe sockets, and thus the entire internal surface of the sand mould willhave been compacted, after the head 34 has travelled from the blow headend of the flask to lie within the first socket forming sleeve.

At this stage in the method, the sand mould has now been formed and theplate 21 may be retracted. The

flask will then be disengaged from the blow head 6 and the flask movedon rails 3 to a further station for further processing and eventuallyfor use in the formation of a cast iron pipe.

A further flask will then be moved on rails 3 to the sand mould formingstation and the method repeated for the formation of a further sandmould.

Various advantages accrue from the present invention, for example, apipe mould is formed which is more accurate in its dimensions thanprevious moulds. This is brought about primarily by the positiveclamping of the flask during the formation of the mould and the accuratepositioning of the mandrel and its head. A further advantage is that theformed mould has increased hardness allowing for centrifugally castingheavy weight cast iron pipes without distortion or swelling in themould.

I claim:

1. A method of forming a sand mould for use in the manufacture of apipe, including the steps of locating one end of a cylindrical flaskagainst a sand blow head,

moving a plate carrying a first socket forming sleeve and compactingring so that the plate locates against the other end of the flask,

feeding a cylindrical mandrel having an oversized head through anaperture in the plate until the head enters a second socket formingsleeve mounted on the blow head,

blowing sand into the space formed between the flask and mandrel therebycompacting the sand and blow-forming a pipe mold,

compacting the sand at each end of the flask by longitudinal movement ofthe compacting ring and second socket forming sleeve within the flask,and

withdrawing the mandrel from the second socket forming sleeve throughthe formed pipe mold and to the first socket forming sleeve whilemaintaining said plate with said first socket forming sleeve in placeagainst said other end of the flask whereby said head further compactsand smoothes the inner wall of the sand of the pipe mold.

2. In apparatus for forming a sand mold for use in the manufacture of apipe,

a cylindrical flask within which sand is molded,

a sand blow head for the injection of sand into said flask to form apipe mold,

means for causing relative movement between said flask and said sandblow head whereby the sand blow head is attached to and closes one endof said flask,

a plate movable towards and away from said blow head to clamp said flaskbetween said plate and said blow head and close the other end of saidflask,

a first socket forming sleeve carried by said plate and positioned toenter said flask on clamping thereof,

a compacting ring carried by said plate, means for moving saidcompacting ring relative to said plate axially of said flask,

a secondsocket forming sleeve mounted on said blow head and positionedto enter said flask on clamping thereof,

means for moving said second socket forming sleeve relative to said blowhead axially of said flask for compacting sand in the flask,

a mandrel having an oversized head for compacting the inner wall of asand mold, said mandrel being axially movable relative to said plate andsaid first socket forming sleeve, and

means for moving said mandrel within a pipe mold blow-formed in saidflask from a position in which said enlarged head has entered saidsecond socket forming sleeve to a position in which said enlarged headhas entered said first socket forming sleeve while maintaining saidplate against said other end of the flask whereby said enlarged headcompacts and smoothes the inner wall of the sand of the pipe mold.

3. In apparatus according to claim 2, in which first and second locationmeans are provided on said blow head and said plate respectively foraccurately positioning said flask on clamping thereof.

4. ln apparatus according to claim'3, in which both said first and saidsecond location means are in the form of a ring having an innerperipheral edge chamfered for reception of said flask.

5. In apparatus according to claim 4, in which said mandrel passesthrough an aperture in said plate, and

means is provided on said blow head for accurately positioning said headof said mandrel in said second socket forming sleeve.

6. In apparatus according to claim 5 in which said means for accuratelypositioning the head of said mandrel in said second socket formingsleeve includes a projection on said blow head which enters a recess insaid head of said mandrel for guiding said head of said mandrel towithin said second socket forming sleeve.

7. In apparatus according to claim 2, in which there is provided a firstpair of piston and cylinder assemblies, and

sliding means on which said plate is mounted, said plate being slidableon said sliding means by actuation of said first pair of piston andcylinder assemblies for moving said plate toward and away from said blowhead.

8. In apparatus according to claim 2, in which there is provided asecond pair of piston and cylinder assemblies connected to saidcompacting ring for effecting movement thereof relative to said plate.

9. In apparatus according to claim 2, in which there is provided asingle piston and cylinder assembly connected to said mandrel and saidenlarged and head for effecting axial movement thereof.

1. A method of forming a sand mould for use in the manufacture of apipe, including the steps of locating one end of a cylindrical flaskagainst a sand blow head, moving a plate carrying a first socket formingsleeve and compacting ring so that the plate locates against the otherend of the flask, feeding a cylindrical mandrel having an oversized headthrough an aperture in the plate until the head enters a second socketforming sleeve mounted on the blow head, blowing sand into the spaceformed between the flask and mandrel thereby compacting the sand andblow-forming a pipe mold, compacting the sand at each end of tHe flaskby longitudinal movement of the compacting ring and second socketforming sleeve within the flask, and withdrawing the mandrel from thesecond socket forming sleeve through the formed pipe mold and to thefirst socket forming sleeve while maintaining said plate with said firstsocket forming sleeve in place against said other end of the flaskwhereby said head further compacts and smoothes the inner wall of thesand of the pipe mold.
 2. In apparatus for forming a sand mold for usein the manufacture of a pipe, a cylindrical flask within which sand ismolded, a sand blow head for the injection of sand into said flask toform a pipe mold, means for causing relative movement between said flaskand said sand blow head whereby the sand blow head is attached to andcloses one end of said flask, a plate movable towards and away from saidblow head to clamp said flask between said plate and said blow head andclose the other end of said flask, a first socket forming sleeve carriedby said plate and positioned to enter said flask on clamping thereof, acompacting ring carried by said plate, means for moving said compactingring relative to said plate axially of said flask, a second socketforming sleeve mounted on said blow head and positioned to enter saidflask on clamping thereof, means for moving said second socket formingsleeve relative to said blow head axially of said flask for compactingsand in the flask, a mandrel having an oversized head for compacting theinner wall of a sand mold, said mandrel being axially movable relativeto said plate and said first socket forming sleeve, and means for movingsaid mandrel within a pipe mold blow-formed in said flask from aposition in which said enlarged head has entered said second socketforming sleeve to a position in which said enlarged head has enteredsaid first socket forming sleeve while maintaining said plate againstsaid other end of the flask whereby said enlarged head compacts andsmoothes the inner wall of the sand of the pipe mold.
 3. In apparatusaccording to claim 2, in which first and second location means areprovided on said blow head and said plate respectively for accuratelypositioning said flask on clamping thereof.
 4. In apparatus according toclaim 3, in which both said first and said second location means are inthe form of a ring having an inner peripheral edge chamfered forreception of said flask.
 5. In apparatus according to claim 4, in whichsaid mandrel passes through an aperture in said plate, and means isprovided on said blow head for accurately positioning said head of saidmandrel in said second socket forming sleeve.
 6. In apparatus accordingto claim 5, in which said means for accurately positioning the head ofsaid mandrel in said second socket forming sleeve includes a projectionon said blow head which enters a recess in said head of said mandrel forguiding said head of said mandrel to within said second socket formingsleeve.
 7. In apparatus according to claim 2, in which there is provideda first pair of piston and cylinder assemblies, and sliding means onwhich said plate is mounted, said plate being slidable on said slidingmeans by actuation of said first pair of piston and cylinder assembliesfor moving said plate toward and away from said blow head.
 8. Inapparatus according to claim 2, in which there is provided a second pairof piston and cylinder assemblies connected to said compacting ring foreffecting movement thereof relative to said plate.
 9. In apparatusaccording to claim 2, in which there is provided a single piston andcylinder assembly connected to said mandrel and said enlarged and headfor effecting axial movement thereof.